A co-ownership established following the publication of a concomitant declaration of co-ownership within in the framework of setting-up a co-ownership by phase. The concomitant co-ownerships are erected on the private portions of the initial co-ownership. Each of them is legally autonomous both for the management and maintenance of its building. This co-ownership type may be vertical (residential tower) or horizontal (townhouse complex). These two layouts can coexist in the same initial co-ownership.